1. Field of the Invention
The invention relates to a dental adhesion-promoting composition, or bonding composition, which contains an acryloyloxyethyl dihydrogen phosphate and/or diacryloyloxyethyl hydrogen phosphate, a photopolymerization catalyst, and an organic solvent.
2. Background Information
When tooth cavities are filled with a polymerizable resin-based tooth filling material, then before the filling is introduced, the tooth enamel is prepared with an acid etching solution, for example a dilute phosphoric acid solution, and is optionally also coated with a sealing material of low viscosity, which typically contains monomeric dimethacrylates and is curable chemically or by photopolymerization, in order to improve the adhesion between the tooth enamel and the resin. Sealing materials that contain a fine-grained inorganic filler in addition to the monomers have proved to be particularly suitable, because of their good physical qualities. Their adhesion is due to mechanical anchoring in the etched tooth enamel.
From the standpoint of the dental practitioner, however, etching of the tooth dentine is not recommended. If anchoring by etching the tooth enamel is impossible, for example in the case of cavities of the neck of the tooth, then adhesion promoters are used to improve the adhesion between the dentine and the resin. Many such dental adhesion-promoting compositions are known, because they play an increasingly large role, given the use of composite fillings. The initial polymerization shrinking of the composite, which causes fissuring between the filling and the hard substance of the tooth, however, is a substantial problem. This allows bacteria to invade, which can damage the pulp and cause secondary caries.
Adhesive Restorative Dental Materials 1961, pp. 195-198, reports on the adhesion-promoting effect of dimethacryloyloxyethyl hydrogen phosphate and various dihydrogen phosphates containing methacryloyloxy groups.
German Examined Patent Application 27 11 234, YAMAUCHI, discloses adhesives for teeth and tooth materials that may contain an acidic phosphoric acid ester, for example, in the form of dimethacryloyloxyethyl hydrogen phosphate, optionally together with other monomers, and polymerization catalysts, for instance in the form of amine/peroxide systems or UV sensitizing agents.
European Patent Application 88 527 describes an adhesion promoter that comprises a solution of a dihydrogen phosphate having at least three methacryloyloxy groups, in a volatile organic solvent, especially an alkanol. Along with this material, a bonding or sealing material ("intermediate bonding resin") may be used to increase the bonding of the tooth filling material to the tooth substance.
Other compositions that improve the bonding of photopolymerizable dental materials to the dentine and likewise contain methacryloyloxyethyl hydrogen phosphates, along with a photopolymerization catalyst are known from German Patents 34 14 163 and 34 14 165 and U.S. Pat. No. 4,640,936, JANDA.
Carboxylic acids and carboxylic acid derivatives containing polymerizable groups which exhibit good adhesion with the hard substance of the tooth are also known, such as 4-methacryloyloxyethyl trimellitic acid and its anhydride, pyromellitic acid dimethacryloyloxyethyl ester, esters of carboxynaphthalene dicarboxylic acid anhydrides containing acryloyloxy or methacryloyloxy groups in the alcohol remainder (U.S. Pat. No. 4,591,649 and German Patent 35 10 962), and omega-(meth)acryloyloxy-alpha, alpha-alkanedicarboxylic acids (European Patent Application 206 810, IWAMOTO et al.).
U.S. Pat. No. 4,806,381 and German Patent Disclosure Document DE-OS 35 36 077, ENGELBRECHT, relate to oligomeric or prepolymeric compounds having both polymerizable unsaturated groups and acid radicals, their salts or their active derivative radicals, and particularly having carboxylate, phosphate, phosphonate, sulfonate and borate radicals and their reactive derivatives. Polymerizable mixtures containing these compounds can be used as adhesion-promoting polymerizable films between the tooth substance and the polymerizable resin material.
The composition described in European Patent Application 282 280, WAKUMOTO, serving to improve the bonding of composite material to the enamel and dentine, contains polymerizable compounds with acid radicals in the molecule, such as aromatic carboxylic acids or phosphoric acids with acryloyloxy or methacryloyloxy groups, for example, 4-methacryloyloxyethoxycarbonylphthalic acid or its anhydride.
The adhesion promoter known from European Patent Application 310 919, YAMAZAKI, for improving the adhesion between the tooth substance and the composite material contains a fluoralkyl ester of acrylic acid, fluoracrylic acid or methacrylic acid and/or its polymer or copolymer, and optionally additionally includes other monomers that improve the adhesion, for example having carboxylic acid, phosphoric acid, mercapto or sulfonic acid groups. It can be cured by chemical polymerization or photopolymerization.